Independent mobility is a key contributor to the quality of life and social participation of an individual with a physical disability. With decreased mobility, there is usually an associated increased risk of social isolation, unemployment, and other health problems, such as obesity, cardiovascular disease, and pressure ulcers. Unimpaired individuals on fitness programs and athletes in training use instruments to measure their progress. Pedometers, for example, are widely used to measure walking distances for the purpose of monitoring physical activity levels and evaluating the attainment of physical activity recommendations. However, there are no commercial "pedometers" for individuals who use wheelchairs. Thus, they cannot objectively quantify levels of physical activity and detect incremental changes as a result of intervention. Researchers at the Human Engineering Research Laboratories have developed two generations of wheelchair dataloggers. These dataloggers have been successfully used to investigate the activity levels of consumers and compare usage among different types of wheelchairs. We have received several requests from research institutions, rehabilitation hospitals and clinics to purchase our second-generation dataloggers. The market appeal for wheelchair dataloggers has also been confirmed through feedback from users, clinicians, therapists, and wheelchair manufacturers and suppliers. In this proposal, we will further improve both our manual and powered wheelchair dataloggers. Improvements will encompass mechanical reliability, electronic updates and software features. It is critical that commercialization of wheelchair dataloggers be accelerated so that it can become more readily available as an outcome measure for researchers, clinicians, wheelchair manufacturers and suppliers, as they all strive to understand how wheelchairs or other related interventions affect mobility levels of users, or how mobility levels relate to other medical/physiological symptoms. This enhanced objective understanding facilitated by dataloggers will lead to early detection and intervention of mobility-induced problems, quantifiable intervention or prescription evaluation, and justification of wheelchairs provided.